Question

Why no hyperconjugation in

Answer 1

hey mate!!⭐⭐⭐

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♐⚡HYPERCONJUGATION:-(permanent effect)

♐♐✓ delocalisation of carbon hydrogen sigma bond to plane it comes in conjugate with c=c , c free redical, cabcations then delocalisation phenomenon is known as hyper conjugation of sigma bond resonance or no bond resonance on Baker Nathan effect.

♐✓ the necessary condition for hyperconjugation is presence of alpha hydrogen it should be attached with SP3 hybrid.

❄️Now coming to ur question...

⚡Why this carbanion will not show hyperconjugation.

✌️⚡⚡Actually ELECTRONEGATIVITY of carbon is greater then that of hydrogen that's why hyperconjugation is not possible in that case.

Hope it will help you...✌️✌️

#phoenix⭐

Answer 2

The answer can be obtained from drawing the relevant resonance structures
Resonance does occur in Benzene regardless of the nature of the substitution. Electron donating groups such as alkyls follow Ortho-Para substitution where as electron withdrawing groups such as nitriles lead to Meta-substitution



As you can see above, the resonance structures for Toluene are shown. They increase the electron density in positions ortho and para to the methyl group making these areas susceptible to attack by electrophiles.




And in benzonitrile, the resonance structures reduce the electron density on the ortho and para positions making the meta position relatively electron rich. Therefore, electrophiles would attack the meta position.

Now considere the case of meta xylene, the resonance structures would look as follows